Contactless heater floating zone refining and crystal growth
AssigneeWisconsin Alumni Research Foundation
InventorsSindo Kou, Chung-Wen Lan
Life of this patent
Estimating the term…
Abstract
Floating zone refining or crystal growth is carried out by providing rapid relative rotation of a feed rod and finish rod while providing heat to the junction between the two rods so that significant forced convection occurs in the melt zone between the two rods. The forced convection distributes heat in the melt zone to allow the rods to be melted through with a much shorter melt zone length than possible utilizing conventional floating zone processes. One of the rods can be rotated with respect to the other, or both rods can be counter-rotated, with typical relative rotational speeds of the rods ranging from 200 revolutions per minute (RPM) to 400 RPM or greater. Zone refining or crystal growth is carried out by traversing the melt zone through the feed rod.
Claims36
A method of growing a finish rod from a feed rod of material comprising the steps of:
- (a) establishing a melt zone between an initial finish rod section and the feed rod;
- (b) providing relative rotation of the feed rod and finish rod with respect to each other at a speed at least as great as 200 rpm while applying heat to the melt zone sufficient to maintain the melt zone;
- (c) traversing the feed rod with the melt zone while maintaining rotation of the feed rod and finish rod with respect to each other and applying heat to the melt zone sufficient to maintain the melt zone.
A method of growing a finish rod from a feed rod of material comprising the steps of:
- (a) establishing a melt zone between the feed rod and an initial section of the finish rod;
- (b) providing rapid relative rotation of the feed rod and finish rod with respect to one another at a selected speed while applying a selected heat to the melt zone, the speed of rotation of the rods relative to one another and the amount of heat applied to the melt zone being selected such that the aspect ratio of the melt zone is less than about 0.7;
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- (c) traversing the feed rod with the melt zone to grow the finish rod from the molten material in the melt zone.
A method of growing a finish rod from a feed rod of material comprising the steps of:
- (a) mounting the feed rod and an initial section of finish rod for rotation with facing ends of the two rods spaced closely together;
- (b) applying heat to the facing ends of the two rods to melt the material of the facing ends;
- (c) then bringing the two rods closer together to join the melted material on each rod to establish a melt zone between the two rods while providing a slow speed of rotation of the rods relative to one another;
- (d) then providing rapid relative rotation of the feed rod and finish rod with respect to one another at a selected speed while applying a selected heat to the melt zone, the speed of rotation of the rods relative to one another and the amount of heat applied to the melt zone being selected such that the melt zone is stable.
A method of growing a finish rod from a feed rod of material comprising the steps of:
- (a) establishing a melt zone between the feed rod and an initial section of the finish rod;
- (b) providing rapid relative rotation of the feed rod and finish rod with respect to one another at a selected speed while applying a selected heat to the melt zone, the speed of rotation of the rods relative to one another and the amount of heat applied to the melt zone being selected such that the melt zone is stable, the melt/solid interfaces of the two rods do not contact each other, and at least one of the interfaces is substantially flat at its center;
- and
- (c) traversing the feed rod with the melt zone to grow the finish rod from the molten material in the melt zone.
Dependencies are inferred from the claim text.